E90-1s have plate scratches too!

[steve B]

Originally Posted by OLDBILL

Although not very savvy about the T206's, are the scratches just on the backs? If so, is this related to the fact that just the fronts were coated during the lithography process?

For both T206s and E90's, the scratches found so far and studied just happen to be on the backs.

They were printed from stones, which weighed a lot being 2-4 inch thick pieces of limestone. A bit of debris could scratch the stone, leaving an area that would now hold ink.


It's probable that the scratched ones were mostly backs for a few reasons,

The back stone got used for a much longer time- as we've seen, on multiple different front sheets.

Being single color, and an ad, the scratches probably didn't merit redoing the whole stone. A scratch creating a line of color on the front might have. (Plus, there were at least 6 front stones)


Not all front problems got fixed, and it's probable that each position can be identified. Generally a scratch will correspond with any flaws found on the front. A real find would be a front with a flaw that doesn't have the scratch on the back. That would mean that that particular exact subject/position was printed both before and after the scratch happened.

Pat would know better, but I don't think any have been found.

[judsonhamlin]

Joss pitching plate scratches

[Leon]

Nice info on the process...

Originally Posted by steve B

For both T206s and E90's, the scratches found so far and studied just happen to be on the backs.

They were printed from stones, which weighed a lot being 2-4 inch thick pieces of limestone. A bit of debris could scratch the stone, leaving an area that would now hold ink.


It's probable that the scratched ones were mostly backs for a few reasons,

The back stone got used for a much longer time- as we've seen, on multiple different front sheets.

Being single color, and an ad, the scratches probably didn't merit redoing the whole stone. A scratch creating a line of color on the front might have. (Plus, there were at least 6 front stones)


Not all front problems got fixed, and it's probable that each position can be identified. Generally a scratch will correspond with any flaws found on the front. A real find would be a front with a flaw that doesn't have the scratch on the back. That would mean that that particular exact subject/position was printed both before and after the scratch happened.

Pat would know better, but I don't think any have been found.

[OLDBILL]

Yes, thank you Steve B! I was originally thinking that the front coating might have made it less vulnerable to scratches than scratches on the back. Although your explanation certainly seems the best, I was also thinking that the scratches might have occurred when the back pages were not cleanly lifted/removed/slid off the print plate.

Bill

[steve B]

That sort of mark does happen, but it's less common. Those are also usually inconsistent. They may be in the same general area, but hardly ever the same. I have some on modern cards, but not on older ones.

The stone would be dampened, inked, then it prints to a rubber roller that is what actually touches the sheet. Lots of stuff can happen there too. Like cracks in the rubber if it isn't changed when it needs to be. But those show as white lines. (It's also very uncommon. )